Synthesis, characterization and biological evaluation H C...

C H A P T E R 1 P a g e | 1

Ph. D. Thesis (2012), Mr. Kamlesh R. Desale School of Chemical Sciences, NMU, Jalgaon.

Chapter 1 Synthesis, characterization and biological evaluation

of (E)-3-Benzylidene-dihydro-5-methylfuran-2(3H)-ones

as potential anti-cancer and anti-oxidant agents.

1.1 Introduction

The γ-butyrolactone (GBL) moiety is part of many oxygenated natural

heterocycles [1]

and secondary metabolites [2]

, especially in sesquiterpene lactones [3]

and lignans [4]

. The representative members shown below exemplify the structural

diversity found within this class of products. These includes Tulipalin A (1) [5]

the

smallest member of this class of natural product, Alantolactone (2) [6]

and Euparotin

(3) [7]

(Figure 1.1).

O

O

O

O

O

O

HO

HO

H

O

OO

1 2 3

Fig. 1.1

This unit is also present in insect pheromones [8]

and in the essential oils

Jasmin floewrs [9]

. γ-Butyrolactones (GBL’s) are an important class of compounds

because they are easily transformed into butenolides, furans, cyclopentanones [10]

etc.

They also serve as valuable building blocks for the synthesis of various types of

natural products and biologically active substances [11]

. The GBL’s are known to

posses significant biological activities. The biological activities of such compounds



may be due to α, β-unsaturated carbonyl moiety, which in turn act as a Michael

acceptor towards different biological nucleophiles.

1.2 Naturally occurring γ-butyrolactones

The γ-butyrolactone (GBL) moiety is widely present in nature. It will be

isolated from natural sources i.e. from plants and fungases. Some of the GBL’s which

are isolated from the nature are demonstrated as follows;

1.2.1 Piper philippinum is a woody climber found throughout the Philippines and

Lanyu and Lutao Islands in Taiwan [12]

. The n-hexane and chloroform soluble

fractions of stem extract of this plant led to the isolation of five new GBL’s,

Piperphilippinins (4-8) [13]

as shon in Figure 1.2.

O

O

HO

HO

H3CO

OH

O

O

HO

HO

O

O

H3CO

HO

H3CO

OCH3

O

O

HO

HO

O

O

HO

H3CO

OH

O

O

OCH3

OCH3

O

O

4 5 6

7 8

Fig. 1.2



1.2.2 The Calocedrus formosana, is a member of Cupressaceae indigeous in Taiwan

[14]. The acetone extracts of this wood Calocedrus formosana give’s seven GBL’s 9-

15 [15]

as shown in Figure 1.3.

O

O

O

O

O

O

O

O

O

O

O

O

H

O

O

O

O

O

O

OH

O

O

H3CO

HO

OH

OCH3

O

OO

O

O

O

O

O

O

H3CO

H3CO

OH

OCH3

OH

O

O

H3CO

HO

OH

OCH3

OCH3

9 10 11

12 13 14

15

Fig. 1.3

1.2.3 Solanum khasianum Clarke is a native plant of India. It is found in the flora of

the South-Estern sub-Himalayan region of the Indo-Burma biodiversity belt [16]

, an

unusal long chain alkylated α-methylene-γ-butyrolactone (16) (Figure 1.4) was

isolated from the juice of its ripe fruit [17]

.



OO

H

H

H

H

H

16

Fig. 1.4

1.2.4 The four new GBL’s Bombardolides A-D [18]

(17-20) were isolated from the

organic extracts from cultures of the coprophilous fungus Bombardioidea anartia.

They are as shown below in Figure 1.5.

O

O

HO

O

O

HO

O

O

HOOC

17 18

19

O

O

HO

20

Fig. 1.5

1.2.5 The closest known structural analogue of the bombardolides is Lissoclinolide

(21) (Figure 1.6) an anti-bacterial metabolite. It is isolated from the tunicate

Lissoclinum patella [19]

.



O

O

HO

OH21

Fig. 1.6

1.2.6 Litsea japonica is an evergreen tree found in the Southern areas of Korea and

Japan [20]

. The following five lactones [21]

(Figure 1.7), Litsealactone A (22),

Litsealactone B (23), Hamabiwalactone A (24), Hamabiwalactone A (25) and

Akolactone B (26) were isolated from the leaves of this plant.

O OO O

HO

22 23

O O O O

24 25

O O

26

Fig. 1.7



1.3 Biological activities of γ-butyrolactones

Several naturally occurring as well as synthetic γ-butyrolactones are well

known for their various biological activities. These compounds displayed a very broad

spectrum of biological activities including anti-cancer [22]

, anti-viral HIV-I [23]

, anti-

inflammatory [24]

, anti-platelet [25]

, anti-fungal [26]

, anti-bacterial [27]

, phytotoxic [28]

,

anthelminthic acivity [29]

and allergenic activity [30]

. Among all the above activities

some of them are described in brief as follows;

1.3.1 Anti-tumoral activity

Vernolepin (27) [31]

, Aromaticin (28) [32]

and Elephantopin (29) [33]

are the

active sesquiterpene lactones have been isolated from plant extracts which show Anti-

tumoral activity [34, 35]

(Figure 1.8). It has been shown that almost all the known

cytotoxic sesquiterpene lactones posses an α, β-unsaturated lactone structure, and that

the conjugated double bond must be exocyclic.Podophyllotoxin (30) is a known anti-

tumor lactone [36]

(Figure 1.8).

O

O

OH

O

OH

O

O O

H

O

O

O

O

OO

O

O

O

O

O

OH

OCH3

H3CO OCH3

27 28

29 30

Fig. 1.8



1.3.2 Allergenic activity

The sesquiterpene lactone Parthenin [[37]

] (31) (Figure 1.9), present in the

pollen of Parthenium hysterophorous is a primary allergen. The aalurgy thus caused a

serious dermatological problem [37]

. The presence of α-methylene-γ-butyrolactone

moiety is a sufficient requirement for the aalergic activity.

O

O

O

OH

31

Fig. 1.9

1.3.3 Phytotoxic and Anti-microbial activities

Phytotoxic activities are also shown by the number of sesquiterpene lactones.

Heliangin (32) is the example of such class of sesquiterpene lactones (Figure 1.10).

This is a germacranolide present in the tuberous sunflower which causes plant growth

inhibition [38, 39].

Xanthatin (33) (Figure 1.10) is also used in the regulation of plant

growth [40]

.

O

O

HO

O

O

O

O

O

O

32 33

Fig. 1.10



1.4 Synthetic utility of α-ylidene-γ-butyrolactones

O

O

R

R1

34

R= aryl (34A), alkyl (34B)

R1= H, CH3, CH2O

α-Arylidene- (34A) and α-alkylidene-γ-butyrolactones (34B) have been used

as a versatile building block for the synthesis of various kinds of natural products and

biologically active compounds [41]

. For example Gomisin [42]

(35), Schizandrin [42]

(36), (+) Deoxypodorhizan [43]

(37), (-) Podorhizon [44]

(38), (±) Ancespsenolide [45]

(39), (±) Jatrophan [46]

(40), (±) Savinin [47]

(41), (±) Gadian [48]

(42), (+) Cycloolivil

[49] (43) and (-) Hinokinin

[50] (44) as shon in Figure 1.11.

The various examples are demonstrated as follows;



O

O

R

R1

R = aryl, alkyl

R1 = H, CH3, CH2O

H

OH

H3CO

H3CO

H3CO

H3CO

35

H

OH

H3CO

H3CO

H3CO

H3CO

H3CO

H3CO

36

O

O

O

OH

OCH3

H3CO OCH3

37

O

O

O

OH

OCH3

H3CO OCH3

38

O

O

O

O

O

10

39

O

O

O

OCH3

OCH3

O

40

O

O

41

O

O

O

O

42

O

O

OH

OH

H

OH

OH

OCH3

HO

H3CO

43

O

O

44

O

O

O

O

O

O

H

H

O

O

Fig. 1.11

1.5 Synthesis of (E) - α-ylidene-γ-butyrolactones

In view of natural occurrence and various applications including biological as

well as synthetic, several methods have been developed and reported in literature for

the synthesis of α-ylidene-γ-butyrolactones. Some of the important methods are

depicted as below;

C H A P T E R 1 P a g e | 10


1.5.1 Minami et al have synthesized [51] α -ylidene-γ-butyrolactone using Wittig-

Horner reaction. In this approach α - (O, O-diethy1phosphono)-y-butyrolactone

carbanion [52]

is first treated with sodium hydride. The anion generated in situ was

then reacted with aldehydes to afford a mixture of E- and Z- ylidene-γ-butyrolactones

(Scheme 1).

O

O

PEtO

O

EtO + R-CHO O

O

RNaH / dry C6H6

50-600C2.5 hrs reflux E- and Z-

R = alkyl, aryl

1.5.2 Matsuda et al synthesized [53]

the α-ylidene-γ-butyrolactones by making the

use of α-cyano carbanion which were generated from γ-trimethylsiloxy nitriles. These

anions were reacted with aldehydes to give α-(1-hydroxyalkyl)-γ-trimethylsiloxy

nitriles, which on lactonisation followed by dehydration provided α -ylidene-γ-

butyrolactones. Using this approach they have synthesized both α-alkylidene and α-

arylidene-γ-butyrolactones (Scheme 2).

R1 CN

OSi(CH3)3

R1 CN

OSi(CH3)3

R1

OSi(CH3)3

CN

OH

R2

O

O

R2

OH

R1

O

O

R2

R1

H

LDA / THF

-780C

1. R2-CHO

2. NH4Cl

1.5M HCl

CH3SO2Cl

pyridine, reflux

R1 = H, alkyl

R2 = H, alkyl, phenyl

1.5.3 In a modified approach developed [54]

by Sanemitsu et al involves the use of γ-

methyl-γ-butyrolactone which was silylated by standard techniques [55]

to give the

corresponding 2-trimethylsiloxy-3-trimethylsilyl-5-methyl-4, 5-dihydrofuran which

C H A P T E R 1 P a g e | 11


was successively hydrolysed using 1.5N HCl to provide α-trimethylsilyl-γ-methyl-γ-

butyrolactone which on condensation with aldehyde in presence of LDA in THF gives

the corresponding α-benzylidene-γ-butyrolactone (Scheme 3).

O

O

O

O

(H3C)3Si

O

O

Ar1. (CH3)3SiOSO2CF3

2. H +1. LDA / THF

2. Ar-CHO

1.5.4 A method developed [45]

by Larson involves condensation of α-

silylbutyrolactone with aldehydes using LDA. The α-silylbutyrolactone was prepared

from γ-butyroactone and diphenylmethylchlorosilane in the presence of LDA

(Scheme 4).

O

O

R1

O

O

R1

O

O

1. LDA / THF / -780C

2. Ph2CH3SiCl

Si

Ph

Ph

H3C

R1 = H, CH3

1. LDA / THF/ -780C

2. R2COR3

R2

R3

1.5.5 Junjappa et al [56]

have developed a streoselective synthesis of α-ylidene-γ-

butyrolactones. They have synthesized the final products in three steps from α-allyl-α-

oxoketene dithioacetals, which were inturn obtained [57]

from the corresponding

propiophenone and dialkyl ketones using a multistep reaction sequence (Scheme 5).

R

O

H3CS SCH3

R1

OH

R

H3CS SCH3

R1

R

H

O OCH3

R1

O

O

R1

R

NaBH4

C2H5OH, CH3OH,

H3PO4

HCOOH,

R = CH3, aryl

R1 = H, CH3

BF3. (C2H5)2O

C H A P T E R 1 P a g e | 12


1.5.6 In another approach developed [58]

by Matsui γ-butyrolactone was treated with

bis [ethoxy (thiocarbonyl)] disulfide in the presence of 2.2 equv. of LDA. The anion

generated was then reacted with an aldehyde to afford (E)- α-alkylidene-γ-

butyrolactone. When it was carried out in the presence of metal complexes such as

zinc chloride, copper (I) iodide or tributyltin chloride, (Z)-α-alkyliden-γ-butyrolactone

was obtained as a major product (Scheme 6).

O

O

O

OLi

R1OCS

O

O

R2

O

O

R2

1. 2.2 eqv. LDA

-780C, 0.5 hr

2. (R1OCS)2, -780C

S

R2-CHO

-780C, 2hr, r.t.

1. 1.5 eqv. MX, 0.5 hr

2. R2-CHO

-780C, 2hr, r.t.

E- only

Z- only

S

H

H

1.5.7 An interesting approach was developed [47]

by Lee et al for the synthesis of

(E)-α-Arylidene-γ-butyrolactones which involves radical addition-elimination

reaction of Z-α-stannylmethylene-γ- butyrolactones, whereas the palladium (O)

catalysed cross-coupling reaction of the same substrates afforded (Z)-α-arylidene-γ-

butyrolactones (Scheme 7).

O

OSnBu3

Ph

+ Ph-I

O

O

Ph

Ph

O

O

Ph

Ph

Bu3SnH, AIBN

C6H6, reflux

Pd(dba)2

tolune, reflux

(E)-only

(Z)- only

1.5.8 The method developed [59]

by Tamaru et al involves palladium (II) catalysed

trans alkoxycarbonylation of 4-alkyl- and 4-aryl-3-butyn-1-ols in the presence of

propylene oxide and ethyl orthoacetate in methanol under carbon monoxide at

atmospheric pressure (Scheme 8).

C H A P T E R 1 P a g e | 13


H3C OH

R CO (1 atm)

PdCl2CuCl2 (3 equv.)

propylene oxide (5 equv.)

CH3C(OC2H5)3 (0.4 equv.)

CH3OH, r.t.

O

O

CH3

OCH3

R

R = alkyl, aryl

1.5.9 An approach developed [60]

by Honda et al, involves condensation of optically

active β-benzyl-γ-butyrolactone with aryl aldehydes using LDA, followed by

dehydration of the hydroxylactone using methane sulfonyl cjloride and DBU. This

approach has been used for the chiral synyhesis of lignan lactone (Scheme 9).

C H A P T E R 1 P a g e | 14


O

O

1. CCl3COCl, POCl3 Zn-Cu, C2H5O, r.t. O

O O

1. PhCHNHCHPh / THF

n-BuLi, -780C

2. (C2H5)3SiCl, -780C

O

O OSi(C2H5)3

1. O3, CH3OH, -780C

2. NaBH4, HCl

O

O

O

O

LDA/ THF, -780C

piperonal

CH3SO2Cl, (C2H5)3N

CH2Cl2, 00C

O

O

O

O

O

O

(CH3)2SO

DBU / CH3CN, r.t.

O

O

O

O

O

O

2. Zn, AcOH, reflux

LDA/ THF, -780C

piperonyl bromide

O

O

O

O

O

O

O

O

O

O

O

O

HO

+ O

O

O

O

O

O

CH3 CH3

1.5.10 Rossi et al developed [61]

a method for the synthesi of E- and Z-, α-ylidene-γ-

butyrolactones which involves palladium mediated cross coupling reactions between

organostannanes [62]

and organic halids (Scheme 10).

C H A P T E R 1 P a g e | 15


X

COOC2H5R1

R2

+

X = Br, I R3 = alkenyl

PdCl2(PhCN)2, CUl

AsPh3, NMP, 20-800C

1. (c-C6H11)2BH.THF

2. H2O2, NaOH

3. -cyclohexanol, +H3O+

4. p-TsOH, C6H6

R1 = H, R2 = alkyl, phenyl

R1 = alkyl, phenyl, R2 = H

R2

COOC2H5R1

O

OR1

R2

R3SnBu3

1.5.11 Ballini et al developed [63]

a convienent method for the synthesis of γ-

substituted-γ-butrolactones starting from nitroalkanes and methyl trans-4-oxo-2-

pentenoate. The steps vsualised for ths conversion are as sown in (Scheme 11).

NO2

R R1

+

O

OCH3

O

DBU / THF, r.t OCH3

O

O

NO2

R

R1

H

-HNO2

OCH3

O

O

R1

R

1. Na2HPO4.12H2O

NaBH4, CH3OH

00C-r.t

1.CeCl3, R2MgBr

THF, -700C

2. AcOH, 10%

OH

OCH3

OR1

R

O

OR1

R

R2

R = C6H5, R1 =H

r

O

OR1

R

R = C6H5, R1 = H, R2 = CH3(CH2)2

6M HCl

C H A P T E R 1 P a g e | 16


1.5.12 Tilve et al developed [64]

a convenient method for the synthesis of volatile

Streptomyces lactones. The steps involved in the synthesis are domino primary

alcohol oxidation–Wittig reaction and acid-catalysed lactonisation (Scheme 12).

R-CH2OHPCC-NaOAC

Ph3PCOOC2H5

COOC2H5

R

H

H+

O

O

R

R = H, CH3

1.6 Present work

As discussed above several natural as well as synthetic α-ylidene-γ-

butyrolactones show useful biological activities and have various synthetic

applications. Although there are various methods have been reported for the synthesis

of title compounds, but if we carefully observed these methods then we find that these

methods either involves mulitistep reaction sequence, used expensive chemicals,

reagents and provided the final product in low yield. In some cases the target lactones

are obtained as a mixture of E- and Z- isomers. There for it was planned to develop a

convienent method for the synthesis of α-ylidene-γ-butyrolactone (34A) using

phosphorane approach. The strategy visualized for the synthesis of α-ylidene-γ-

butyrolactone (34A) utilizing phosphorane approach is shown in Scheme 13.

H

OR1

R2

R3

R4

Ph3P

COOC2H5

R1

R2

R3

R4

O

O

R1

R2

R3

R4

O

OH

R1

R2

R3

R4

O

O

45 (a-j)

47

48 (a-j)

49 (a-j)34A (a-j)

dry benzene / reflux

3N KOH / C2H5OH

Stirr, r.t.

Con. H2SO4

Stirr, -100C-00C

HBHX

HA

HM

R5R5

R5R5

Scheme 13

C H A P T E R 1 P a g e | 17


The pentenoates 48a were obtained by the Wittig olefination of benzaldehyde

45a with phosphorane ethyl 2-(triphenyl-λ5-phosphanylidene) pent-4-enoate 47 in

refluxing dry benzene. The reaction was completed in 3.5 hrs. A thick yellowish

liquid product 48a was obtained with 90 % yield after chromatographic separation

using hexane: ethyl actetate as an eluent (9:1). In its IR (KBr, cm-1

) (Figure 1.12)

spectrum it exhibited a peak at 1708 cm-1

which could be assigned to the α, β-

unsaturated ester carbonyl. In the 1H-NMR (CDCl3, 300 MHz) (Figure 1.13) it

showed a triplet (J=7.3 Hz) at 1.34 δ for three protons and a quartet (J=7.3 Hz) at 4.27

δ for two protons which indicated the presence of -OCH2CH3 group. A broad doublet

(J=5.4 Hz) at 3.29 δ for two protons and two mulitiplates at 5.07-5.14 δ and 5.94-6.07

δ for two and one proton respectively indicated the presence of -CH2-CH=CH2 group

attached to carbon. In the aromatic region a multiplate at 7.32-7.42 δ was obtained for

five aromatic protons. Also it exhibited a singlet at 7.80 δ for one proton, which could

be attributed to the olefinic proton (HM). Also the LC-MS spectra of pentenoates 48a

(Figure 1.14) clearly gives the peak at 217.00 (M +H)+. On the basis of the spectral

data the structure 48a could be assigned to it.

C H A P T E R 1 P a g e | 18


O

O

48

a

Fig

. 1.1

2 I

R (

KB

r, c

m-1

) sp

ectr

a of

Com

poun

d 4

8a

.

C H A P T E R 1 P a g e | 19


O

O

48a

HM

Fig

. 1.1

3 1

H-N

MR

(C

DC

l 3, 300 M

Hz,

δ)

spec

tra

of

Com

pound 4

8a

.

C H A P T E R 1 P a g e | 20


O

O

48a

Fig

. 1.1

4 L

C-M

S s

pec

tra

of

Com

pound 4

8a.

C H A P T E R 1 P a g e | 21


It is reported [65]

that the reaction of aldehydes with the phosphorane 47

provides the E- ester exclusively. The geometry of the present pentenoate 48a was

established on the basis of its 1H-NMR spectral properties. The geometry was also

supported by the calculated value of the olefinic β-proton. In the 1H-NMR spectra of

48a olefinic β-proton (HM) appears as singlet at 7.80 δ. This chemical shift is closer to

the calculated [61]

value for the E-isomer (7.53-7.59 δ) rather than that for the Z-

isomer (6.96 δ). Therefore, the pentenoate 48a must have E-configuration.

The phosphorane 47 required for this purpose was synthesized using the

procedure developed [65]

earlier as shown below;

Br

O

O 1. PPh3, dry benzene

2. aq. NaOHPh3P

COOC2H5

H

Ph3P

COOC2H5

Br

CHCl3 /

2. aq. NaOH

1.

46

47

Scheme 14

The simple phosphorane 46 was first prepared using triphenylphosphine and

ethylbromoacetate. The phosphorane 46 was then allylated using allylbromide and the

salt thus obtained was reacted with aq. Sodium hydroxide to afford modified Wittig

reagent that is desired phosphorane 47.

The allyl ester 48a was hydrolysed using ethanolic solution of 3N potassium

hydroxide at room temperature. The pentenoic acid 49a, mp 900C (lit.

[66] 90-91

0C)

was obtained in yield 92 %. The structure of the pentenoic acid 49a was established

on the basis of IR (Figure 1.15), 1H-NMR (Figure 1.16) and LC-Mass (Figure 1.17)

spectral properties as given below;

C H A P T E R 1 P a g e | 22


IR (KBr, cm-1

) : 2958, 1672.

1H-NMR (CDCl3, 300 MHz) δppm :

3.32 brd d (J= 5.4 Hz) 2H (-CH2-CH=CH2)

5.12-5.19 m 2H (-CH2-CH=CH2)

5.98-6.11 m 1H (-CH2-CH=CH2)

7.34-7.47 m 5H (5ArH)

7.96 s 1H (HM)

MS (m/z) : 189.00 (M +H)

+.

C H A P T E R 1 P a g e | 23


O

OH

49a

HM

Fig

. 1.1

5 I

R (

KB

R, cm

-1)

spec

tra

of

Com

pound 4

9a.

C H A P T E R 1 P a g e | 24


O

OH

49

a

Fig

. 1.1

6 1

H-N

MR

(C

DC

l 3, 300 M

Hz,

δ)

spec

tra

of

Com

pound 4

9a

.

C H A P T E R 1 P a g e | 25


O

OH

49

a

Fig

. 1.1

7 L

C-M

S s

pec

tra

of

Com

pound 4

9a.

C H A P T E R 1 P a g e | 26


For lactonisation, the pentenoic acid 49a was reacted with ice cold con.

H2SO4. The reaction was completed in 1.5 hrs as indicated by TLC and the desired

lactone 34Aa, mp 550C (lit.

[66] 58

0C) was obtained in yield 92 %. The structure of the

α-benzylidene-γ-butyrolactone 34Aa was established on the basis of IR (Figure 1.18),

1H-NMR (Figure 1.19), LC-Mass (Figure 1.20) and

13C-NMR (Figure 1.21) spectral

properties as given below;

IR (KBr, cm-1

) : 1737


1.48 d (J= 6.2 Hz) 3H (-CH3)

2.80 ddd (JAB = 17.5, JBX = 5.4, JBM = 2.9 Hz) 1H(HB)

3.35 ddd (JAB = 17.2, JBX = 7.6, JBM = 2.9 Hz) 1H(HA)

4.76 sext 1H(HX)

7.39-7.51 m 5H(5ArH)

7.57 s 1H(HM)

MS (m/z) :189.00 (M +H)+.

13C-NMR (CDCl3, 75 MHz) δppm :172.0-C1, 136.4-C2, 134.6-C3, C3’,

129.8-C4, C4’, 128.8-C5, 124.8-C6, C6’, 74.0-C7, 35.2-C8, 22.3-C9.

C H A P T E R 1 P a g e | 27


OO

HBHM

HX

HA

34A

a

Fig

. 1.1

8 I

R (

KB

R, cm

-1)

spec

tra

of

Com

pound 3

4A

a.

C H A P T E R 1 P a g e | 28


OO

HBHM

HX

HA

34A

a

Fig

. 1.1

9 1

H-N

MR

(C

DC

l 3, 300M

Hz,

δ)

spec

tra

of

Com

pound 3

4A

a.

C H A P T E R 1 P a g e | 29


OO

HBHM

HX

HA

34A

a

Fig

. 1.2

0 L

C-M

S s

pec

tra

of

Com

pound 3

4A

a.

C H A P T E R 1 P a g e | 30


23

4 5

6

78

9OO

HMHBHA

HX

13'

4'

6'

34

Aa

Fig

. 1.2

1 1

3C

-NM

R (

CD

Cl 3

, 75M

Hz,

δ)

spec

tra

of

Com

pound 3

4A

a.

C H A P T E R 1 P a g e | 31


The route presented in Scheme 13 for the synthesis of α-benzylidene-γ-

butyrolactone 34Aa was found to be useful as it provided the lactone 34Aa in three

steps from easily available benzaldehyde 45a. The over all yield of lactone 34Aa from

benzaldehyde 45a in three steps was found to be 74.52 %.

After successful completion of the synthesis of α-benzylidene-γ-butyrolactone

34Aa; it became worthwhile to check the generality of this approach for the synthesis

of other various α-benzylidene-γ-butyrolactone 34A (b-j) using similar reaction

sequence as shown in Scheme 13.

When the various aromatic aldehydes 45 (b-j) were reacted with phosphorane

47 in refluxing dry benzene for 3-3.5 hrs the esters 48 (b-j) were obtained as thick

liquids in 85-94% yield. The structures of all these esters 48 (b-j) were determined on

the basis of their analytical, IR, 1H-NMR and LC-MS spectral data which are given

below;

(E)-Ethyl 2-(4-methoxybenzylidene) pent-4-enoate (48b) [66]

:

HM

O

O

H3CO

HB

HA

HD

HC

Mol. Formula: C15H18O3, Mol. Wt.: 246.3, Yellowish Thick Oil, TLC:

hexane: ethyl acetate (8:2, v/v), Yield: 92 %.

IR (KBr, cm-1

) : 1703


1.33 t (J= 6.9 Hz) 3H (-OCH2-CH3)

3.30 d (J= 5.4 Hz) 2H (-CH2-CH=CH2)

3.83 s 3H (-OCH3)

4.26 q (J= 6.9 Hz) 2H (-OCH2-CH3)

5.08-5.14 m 2H (-CH2-CH=CH2)

5.94-6.07 m 1H (-CH2-CH=CH2)

6.91 d (J= 8.7 Hz) 2H (HA and HB)

7.39 d (J= 8.4 Hz) 2H (HC and HD)

7.76 s 1H (HM)

MS (m/z) :247.05 (M +H)+.

C H A P T E R 1 P a g e | 32


(E)-Ethyl 2-(3, 4-dimethoxybenzylidene) pent-4-enoate (48c) [66]

:

HM

O

O

H3CO

H3CO

HA

HC

HB

Mol. Formula: C16H20O4, Mol. Wt.: 276.33, Yellowish Thick Oil. TLC:


IR (KBr, cm-1

) : 1703


1.33 t (J= 7.3 Hz) 3H (-OCH2-CH3)

3.33 brd d (J= 5.4 Hz) 2H (-CH2-CH=CH2)

3.90 s 6H (2 X -OCH3)

4.26 q (J= 7.3 Hz) 2H (-OCH2-CH3)

5.09-5.16 m 2H (-CH2-CH=CH2)

5.97-6.09 m 1H (-CH2-CH=CH2)

6.87 d (J= 8.4 Hz) 1H (HA)

6.99-7.05 m 2H (HB and HC)

7.76 s 1H (HM)

MS (m/z) :277.05 (M +H)+.

(E)-Ethyl 2-(3, 4, 5-trimethoxybenzylidene) pent-4-enoate (48d) [66]

:

HM

O

O

H3CO

H3CO

OCH3

HB

HA



IR (KBr, cm-1

) : 1708


1.34 t (J= 7.3 Hz) 3H (-OCH2-CH3)

C H A P T E R 1 P a g e | 33


3.32 d (J= 5.1 Hz) 2H (-CH2-CH=CH2)

3.84 s 6H (2 X -OCH3)

3.86 s 3H (1 X –OCH3)

4.27 q (J= 7.3 Hz) 2H (-OCH2-CH3)

5.10-5.17 m 2H (-CH2-CH=CH2)

5.98-6.11 m 1H (-CH2-CH=CH2)

6.67 s 2H (HA and HB)

7.75 s 1H (HM)

MS (m/z) :307.05 (M +H)+.

(E)-Ethyl 2-(4-(benzyloxy) benzylidene) pent-4-enoate (48e) [66]

:

O

O

O

HA

HB

HD

HC

HM



IR (KBr, cm-1

) : 1708


1.33 t (J=7.3 Hz) 3H (-OCH2-CH3)

3.31 brd d (J=5.1 Hz) 2H (-CH2-CH=CH2)

4.26 q (J=7.3 Hz) 2H (-OCH2-CH3)

5.09 s 2H (-OCH2Ph)

5.12-5.14 m 2H (-CH2-CH=CH2)

5.94-6.07 m 1H (-CH2-CH=CH2)

6.98 d (J= 8.7 Hz) 2H (HA and HB)

7.33-7.45 m 7H (HC, HD and 5ArH)

7.76 s 1H (HM)

MS (m/z) :323.10 (M +H)+.

C H A P T E R 1 P a g e | 34


(E)-Ethyl 2-(4-ethoxy-3-methoxybenzylidene) pent-4-enoate (48f):

HM

O

O

HA

OCH3

HC

HB

O



IR (KBr, cm-1

) : 1708


1.33 t (J= 6.9 Hz) 3H (-COOCH2-CH3)

1.47 t (J= 6.9 Hz) 3H (-OCH2-CH3)

3.33 brd d (J= 5.4 Hz) 2H (-CH2-CH=CH2)

3.85 s 3H (-OCH3)

4.12 q (J= 6.9 Hz) 2H (-OCH2-CH3)

4.26 q (J= 6.6 Hz) 2H (-COOCH2-CH3)

5.09-5.16 m 2H (-CH2-CH=CH2)

5.96-6.09 m 1H (-CH2-CH=CH2)

6.86 d (J= 8.0 Hz) 1H (HA)

6.99-7.02 m 2H (HB and HC)

7.75 s 1H (HM)

MS (m/z) :291.15 (M +H)+.

(E)-Ethyl 2-(4-(benzyloxy)-3-methoxybenzylidene) pent-4-enoate (48g):

HM

O

O

O

OCH3

HA

HB

HC


hexane/ethyl acetate (8:2, v/v), Yield: 85 %.

C H A P T E R 1 P a g e | 35


IR (KBr, cm-1

) : 1710


1.33 t (J=7.3 Hz) 3H (-OCH2-CH3)

3.32 brd d (J=5.4 Hz) 2H (-CH2-CH=CH2)

3.87 s 3H (-OCH3)

4.26 q (J=7.3 Hz) 2H (-OCH2-CH3)

5.08-5.15 m 2H (-CH2-CH=CH2)

5.18 s 2H (-OCH2Ph)

5.96-6.08 m 1H (-CH2-CH=CH2)

6.87 d (J=8.0 Hz) 1H (HA)

6.94-7.01 m 2H (HB and Hc)

7.26-7.44 m 5H (5ArH)

7.74 s 1H (HM)

MS (m/z) :353.25 (M +H)+.

(E)-Ethyl 2-(4-(dimethylamino) benzylidene) pent-4-enoate (48h):

NH3C

CH3

HM

O

O

HA'

HA

HB

HB'

Mol. Formula: C16H21NO2, Mol. Wt.: 259.34, Wine Reddish Thick Oil,

TLC: hexane: ethyl acetate (8:2, v/v), Yield: 90 %.

IR (KBr, cm-1

) : 1697


1.32 t (J=7.3 Hz) 3H (-OCH2-CH3)

3.00 s 6H (-N (CH3)2)

3.35 brd d (J=5.1 Hz) 2H (-CH2-CH=CH2)

4.24 q (J=7.3 Hz) 2H (-OCH2-CH3)

5.07-5.16 m 2H (-CH2-CH=CH2)

6.69 d (J= 9.1 Hz) 2H (HA and HA’)

7.38 d (J= 8.7 Hz) 2H (HB and HB’)

7.74 s 1H (HM)

C H A P T E R 1 P a g e | 36


MS (m/z) :260.05 (M +H)+.

(E)-Ethyl 2-(2-nitrobenzylidene) pent-4-enoate (48i):

HM

O

O

HA

NO2

Mol. Formula: C14H15NO4, Mol. Wt.: 261.27, Yellowish Thick Oil, TLC:


IR (KBr, cm-1

) : 1710, 1540.


1.34 t (J=7.3 Hz) 3H (-OCH2-CH3)

3.03 d (J=5.8 Hz) 2H (-CH2-CH=CH2)

4.28 q (J=7.3 Hz) 2H (-OCH2-CH3)

4.90-5.03 m 2H (-CH2-CH=CH2)

5.79-5.92 m 1H (-CH2-CH=CH2)

7.39-7.66 m 3H (3ArH)

7.97 s 1H (HM)

8.13 brd d (J= 9.1 Hz) 1H (HA)

MS (m/z) :262.10 (M +H)+.

(E)-Ethyl 2-((thiophen-2-yl) methylene) pent-4-enoate (48j):

HM

O

O

S

HA

HB

HC

Mol. Formula: C12H14O2S, Mol. Wt.: 222.3, Reddish Thick Oil, TLC:

hexane: ethyl acetate (8:2, v/v), Yield: 92%.

IR (KBr, cm-1

) : 1710.


1.33 t (J= 7.3 Hz) 3H (-OCH2-CH3)

C H A P T E R 1 P a g e | 37


3.46 brd d (J= 5.4 Hz) 2H (-CH2-CH=CH2)

4.26 q (J= 7.3 Hz) 2H (-OCH2-CH3)

5.03-5.18 m 2H (-CH2-CH=CH2)

5.85-5.98 m 1H (-CH2-CH=CH2)

7.07-7.10 m 2H (HM and HB)

7.25-7.29 m 2H (HA and HC)

MS (m/z) :222.95 (M +H)+.

These pentenoic esters 48 (b-j) on basic hydrolysis using ethanolic 3N KOH at

room temperature gives pentenoic acids 49 (b-j). The pentenoic acids 49 (b-j) were

obtained as solids in 89-93% yield. The structures of all these pentenoic acids 49 (b-j)

were determined on the basis of their analytical, IR, 1H-NMR and LC-MS spectral

data which are given below;

(E)-2-(4-methoxybenzylidene) pent-4-enoic acid (49b) [66]

:

HM

OH

O

H3CO

HA

HB

HD

HC

Mol. Formula: C13H14O3, Mol. Wt.: 218.25, White Crystalline solid, TLC:

hexane: ethyl acetate (8:2, v/v), Yield: 93 %, mp: 920C (lit.

[66] 90-91

0C).

IR (KBr, cm-1

) : 2999, 1666.


3.33 brd d (J= 5.1 Hz) 2H (-CH2-CH=CH2)

3.84 s 3H (-OCH3)

5.12-5.18 m 2H (-CH2-CH=CH2)

5.98-6.11 m 1H (-CH2-CH=CH2)

6.91-6.95 m 2H (HA and HB)

7.26-7.45 m 2H (HC and HD)

7.91 s 1H (HM)

MS (m/z) :219.15 (M +H)+.

C H A P T E R 1 P a g e | 38


(E)-2-(3, 4-dimethoxybenzylidene) pent-4-enoic acid (49c) [66]

:

HM

OH

O

H3CO

HA

H3CO

HC

HB



[66] 120

0C).

IR (KBr, cm-1

) : 2968, 1668.


3.35 d (J= 5.1 Hz) 2H (-CH2-CH=CH2)

3.87 s 3H (-OCH3)

3.92 s 3H (-OCH3)

5.14-5.19 m 2H (-CH2-CH=CH2)

6.00-6.11 m 1H (-CH2-CH=CH2)

6.89 d (J= 8.0 Hz) 1H (HA)

7.03-7.09 m 2H (HB and HC)

7.90 s 1H (HM)

MS (m/z) :249.95 (M +H)+.

(E)-2-(3, 4, 5-trimethoxybenzylidene) pent-4-enoic acid (49d) [66]

:

HM

OH

O

H3CO

OCH3

H3CO

HA

HB



[66] 95-97

0C).

IR (KBr, cm-1

) : 2995, 1687.


3.35 d (J= 4.7 Hz) 2 H (-CH2-CH=CH2)

3.85 s 6H (2 X -OCH3)

3.88 s 3H (-OCH3)

C H A P T E R 1 P a g e | 39


5.14-5.20 m 2H (-CH2-CH=CH2)

6.02-6.14 m 1H (-CH2-CH=CH2)

6.71 s 2H (HA and HB)

7.90 s 1H (HM)

MS (m/z) :278.95 (M+H)+.

(E)-2-(4-(benzyloxy) benzylidene) pent-4-enoic acid (49e) [66]

:

HM

OH

O

O

HA

HB

HD

HC



[66] 130-132

0C).

IR (KBr, cm-1

) : 2972, 1670.


3.33 d (J= 5.1 Hz) 2H (-CH2-CH=CH2)

5.10 s 2H (-OCH2Ph)

5.12-5.18 m 2H (-CH2-CH=CH2)

5.98-6.10 m 1H (-CH2-CH=CH2)

7.00 d (J= 8.7 Hz) 2H (HA and HB)

7.34-7.44 m 7H (HC, HD and 5ArH)

7.91 s 1H (HM)

MS (m/z) :295.15 (M +H)+.

(E)-2-(4-ethoxy-3-methoxybenzylidene) pent-4-enoic acid (49f):

OH

OHM

OCH3

HA

HC

HBO

C H A P T E R 1 P a g e | 40



hexane: ethyl acetate (8:2, v/v), Yield: 89 %, mp: 200-2020C.

IR (KBr, cm-1

) : 2937, 1732.


1.48 t (J= 6.9 Hz) 3H (-OCH2-CH3)

3.35 d (J= 4.7 Hz) 2H (-CH2-CH=CH2)

3.86 s 3H (-OCH3)

4.13 q (J= 6.9 Hz) 2H (-OCH2-CH3)

5.14-5.19 m 2H (-CH2-CH=CH2)

6.00-6.11 m 1H (-CH2-CH=CH2)

6.88 d (J= 8.0 Hz) 1H (HA)

7.04-7.06 m 2H (HB and HC)

7.90 s 1H (HM)

MS (m/z) :262.95 (M)+.

(E)-2-(4-(benzyloxy)-3-methoxybenzylidene) pent-4-enoic acid (49g):

HM

OH

O

O

OCH3

HA

HC

HB



IR (KBr, cm-1

) : 2958, 1672.


3.34 d (J= 4.7 Hz) 2H (-CH2-CH=CH2)

3.88 s 3H (-OCH3)

5.17 d (J= 2.1 Hz) 2H (-CH2-CH=CH2)

5.19 s 2H (-OCH2Ph)

5.99-6.11 m 1H (-CH2-CH=CH2)

6.89 d (J= 8.4 Hz) 1H (HA)

6.98-7.05 m 2H (HB and HC)

C H A P T E R 1 P a g e | 41


7.25-7.44 m 5H (5ArH)

7.88 s 1H (HM)

MS (m/z) :325 (M +H)+.

(E)-2-(4-(dimethylamino) benzylidene) pent-4-enoic acid (49h):

OH

OHM

NH3C

CH3 HA

HB

HD

HC

Mol. Formula: C14H17NO2, Mol. Wt.: 231.29, Yellowish Crystalline solid,

TLC: hexane: ethyl acetate (8:2, v/v), Yield: 90 %, mp: 220-2220C.

IR (KBr, cm-1

) :2912, 1658.


3.02 s 6H (-N (CH3)2)

3.37 brd d (J= 5.1 Hz) 2H (-CH2-CH=CH2)

5.11-5.19 m 2H (-CH2-CH=CH2)

5.99-6.11 m 1H (-CH2-CH=CH2)

6.70 d (J= 8.7 Hz) 2H (HA and HB)

7.42 d (J= 8.7 Hz) 2H (HC and HD)

S7.89 s 1H (HM)

MS (m/z) :232.15 (M +H)+.

(E)-2-(2-nitrobenzylidene) pent-4-enoic acid (49i):

HM

OH

ONO2

Mol. Formula: C12H11NO4, Mol. Wt.: 233.22, White Crystalline solid, TLC:


IR (KBr, cm-1

) :2981, 1681, 1540.


C H A P T E R 1 P a g e | 42


3.06 d (J= 5.8 Hz) 2H (-CH2-CH=CH2)

4.96-5.08 m 2H (-CH2-CH=CH2)

5.84-5.97 m 1H (-CH2-CH=CH2)

7.43-8.20 m 5H (HM and 4ArH)

MS (m/z) :234.04 (M +H)+.

(E)-2-((thiophen-2-yl) methylene) pent-4-enoic acid (49j):

OH

OHM

S

HA

HB

HC

Mol. Formula: C10H10O2S, Mol. Wt.: 194.25, White Crystalline solid, TLC:


IR (KBr, cm-1

) :2974, 1666.


3.48 d (J= 5.4 Hz) 2H (-CH2-CH=CH2)

5.06-5.21 m 2H (-CH2-CH=CH2)

5.88-6.01 m 1H (-CH2-CH=CH2)

7.10-7.53 m 3H (HA, HB and HC)

8.05 s 1H (HM)

MS (m/z) :194.95 (M)+.

The acids 49 (b-j) on lactonisation using con. H2SO4 at -10-00C gives α-

benzylidene-γ-methyl-γ-butyrolactones 34A (b-j) as solids in 85-95% yield. The

structures of all these α-benzylidene-γ-methyl-γ-butyrolactones 34A (b-j) were

determined on the basis of their analytical, IR, 1H-NMR, LC-MS and

13C-NMR

spectral data which are given below;

C H A P T E R 1 P a g e | 43


(E)-3-(4-methoxybenzylidene)-dihydro-5-methylfuran-2(3H)-one (34Ab) [66]

:

1

2

3

4

5

5'

6

6' 78

9

10

H3CO

O

O

HC

HD

HF

HB

HM

HX

HA

HE



[66] 76-78

0C).

IR (KBr, cm-1

) :1735.


1.47 d (J= 6.2 Hz) 3H (-CH3)

2.76 ddd (JAB= 17.2, JBX= 5.4, JBM= 2.9 Hz) 1H (HB)

3.37 ddd (JAB= 17.2, JBX= 7.8, JBM= 2.9 Hz) 1H (HA)

3.85 s 3H (-OCH3)

4.75 sext 1H (HX)

6.96 d (J= 8.7 Hz) 2H (HC and HD)

7.45 d (J= 8.7 Hz) 2H (HE and HF)

7.517 s 1H (HM)

MS (m/z) :219.10 (M +H)+.

13

C-NMR (CDCl3, 75 MHz) δppm : 172.4-C1, 160.8-C2, 136.2-C3, 131.7-

C4, 127.4 (2)-C5, C5’, 114.3(2)-C6, C6’, 73.9-C7, 55.3-C8, 35.2-C9, 22.4-

C10.

(E)-3-(3, 4-dimethoxybenzylidene)-dihydro-5-methylfuran-2(3H)-one (34Ac) [66]

:

H3CO

O

O

HB

HM

HX

HA

H3CO 123

45

6

7

8

9

10

2'

10'

11

12



[66] 76-78

0C).

IR (KBr, cm-1

) :1732.

C H A P T E R 1 P a g e | 44



1.48 d (J= 6.5 Hz) 3H (-CH3)



3.91 s 3H (-OCH3)

3.93 s 3H (-OCH3)

4.76 brd sext 1H (HX)

6.91-7.12 m 3H (3ArH)

7.49 s 1H (HM)

MS (m/z) :249 (M +H)+.

13

C-NMR (CDCl3, 75 MHz) δppm : 172.2-C1, 150.4 (2)-C2, C2’, 136.4-C3,

127.6-C4, 123.6-C5, 122.2-C6, 112.6-C7, 111.1-C8, 73.8-C9, 55.8 (2)-C10,

C10’, 35.0-C11, 22.3-C12.

(E)-3-(3, 4, 5-trimethoxybenzylidene)-dihydro-5-methylfuran-2(3H)-one (34Ad)

[66]:

12

3

45

67

8

9

10

2'H3CO

O

O

HB

HM

HX

HA

H3CO

OCH3

4'

8'

8''

6'

Mol. Formula: C15H18O5, Mol. Wt.: 278.3, Brownish Crystalline solid, TLC:


[66] 103-105

0C).

IR (KBr, cm-1

) :1741.


1.49 d (J= 6.2 Hz) 3H (-CH3)



3.89 s 9H (3 X -OCH3)

4.77 sext 1H (HX)

6.71 s 2H (2ArH)

7.48 s 1H (HM)

MS (m/z) :279.15 (M +H)+.

C H A P T E R 1 P a g e | 45


13C-NMR (CDCl3, 75 MHz) δppm : 171.9-C1, 153.2-C2, C2’, 136.5-C3, 130.1-

C4, C4’, 123.7-C5, 107.3-C6, C6’, 73.9-C7, 56.1-C8, C8’, C8’’, 35.0-C9, 22.3-

C10.

(E)-3-(4-(benzyloxy) benzylidene)-dihydro-5-methylfuran-2(3H)-one (34Ae) [66]

:

1

2

3

45

6

78

9

10

6'

O

O

O

HB

HA

HX

HM

HD

HF

HC

HE7'

7'' 7'''

7'''''

7'''' 11

12

8'



[66] 117-120

0C).

IR (KBr, cm-1

) :1722.


1.47 d (J= 6.5 Hz) 3H (-CH3)



4.76 sext 1H (HX)

5.45 s 2H (-OCH2ArH)

6.90 d (J= 8.7 Hz) 2H (HC and HD)

7.26 s 7H (HE, HF and 5ArH)

7.508 s 1H (HM)

MS (m/z) : 295.15 (M +H)+.

13


C4, 131.8-C5, 129.9-C6, C6’, 127.0-C7, C7’, C7’’, C7’’’, C7’’’’, C7’’’’’,

115.8-C8, C8’, 76.3-C9, 74.1-C10, 35.0-C11, 22.2-C12.

C H A P T E R 1 P a g e | 46


(E)-3-(4-ethoxy-3-methoxybenzylidene)-dihydro-5-methylfuran-2(3H)-one

(34Af):

O

O

HB HX

HA

HM

HC

OCH3

O

1

2

3

456

7

8

9

10

1211

13

1415



IR (KBr, cm-1

) :1732.


1.47-1.56 m 6H (-OCH2-CH3 and -CH3)



3.91 s 3H (-OCH3)

4.15 q (J= 6.9 Hz) 2H (-OCH2-CH3)

4.76 sext 1H (HX)

6.91 d (J= 8.0 Hz) 1H (HC)

6.99-7.10 m 2H (2ArH)

7.49 s 1H (HM)

MS (m/z) :263.15 (M +H)+.

13

C-NMR (CDCl3, 75 MHz,) 0-150 δppm: 149.9-C2, 149.2-C3, 136.6-C4,

127.6-C5, 123.7-C6, 122.1-C7, 113.1-C8, 112.3-C9, 73.8-C10, 64.3-C11,

56.0-C12, 35.2-C13, 22.4-C14, 14.6-C15.

(E)-3-(4-(benzyloxy)-3-methoxybenzylidene)-dihydro-5-methylfuran-2(3H)-one

(34Ag):

2

3

4

5

6

7

8

910

1112

13

14

O

O

O

OCH3

HBHX

HA

HM

1

2'

6'

4'5'

5''

5'''

C H A P T E R 1 P a g e | 47


Mol. Formula: C20H20O4, Mol. Wt.: 324.37, Brownish Crystalline solid,


IR (KBr, cm-1

) :1732.


1.48 d (J= 6.2 Hz) 3H (-CH3)



3.94 s 3H (-OCH3)

4.75 sext 1H (HX)

5.88 s 2H (-OCH2ArH)

6.96-7.09 m 3H (3ArH)

7.26 s 5H (5ArH)

7.48 s 1H (HM)

MS (m/z) :325.10 (M +H)+.

13

C-NMR (CDCl3, 75 MHz) δppm : 172.2-C1, 147.2-C2, C2’, 146.5-C3,

136.5-, 131.5, 127.2, 123.8, 121.9-C7, 114.7-C8, 112.4-C9, 76.4-C10, 73.8-

C11, 55.8-C12, 35.1-C13, 22.3-C14.

(E)-3-(4-(dimethylamino)benzylidene)-dihydro-5-methylfuran-2(3H)-one (34Ah):

24

7

8

9

10

15'

N

CH3

H3C

O

OHM

HD

HF

HC

HE

HBHX

HA

35

6

6'

8'

Mol. Formula: C14H17NO2, Mol. Wt.: 231.29, Yellowish Crystalline solid,


IR (KBr, cm-1

) :1732.


1.45 d (J= 6.3 Hz) 3H (-CH3)



3.03 s 6H(-N (CH3)2)

4.72 sext 1H (HX)

C H A P T E R 1 P a g e | 48


6.70 d (J= 9.0 Hz) 2H (HC and HD)

7.39 d (J= 8.8 Hz) 2H(HE and HF)

7.47 s 1H (HM)

MS (m/z) :232.15 (M +H)+.

13

C-NMR (CDCl3, 75 MHz,) 0-150 δppm: 151.0-C1, 137.1-C2, 131.7-C3,

122.5-C4, 118.5-C5, C5’, 111.7-C6, C6’, 73.6-C7, 40.0-C8, C8’, 35.3-C9,

22.4-C10.

(E)-3-(2-nitrobenzylidene)-dihydro-5-methylfuran-2(3H)-one (34Ai):

2

4

7

8

9

10

1356

8'

HMNO2

HC

O

O

HXHB

HA

11

Mol. Formula: C12H11NO4, Mol. Wt.: 233.22, White Crystalline solid, TLC:


IR (KBr, cm-1

) :1747, 1519, 1540.


1.46 d (J= 6.1 Hz) 3H (-CH3)



4.74 sext 1H (HX)

7.49-7.87 m 4H (3ArH and HM)

8.11 d (J= 8.5 Hz) 1H (HC)

MS (m/z) :234.05 (M +H)+.

13


C4, 130.2-C5, 129.9-C6, 129.5-C7, 125.1-C8, 74.4-C9, 34.5-C10, 21.9-C11.

C H A P T E R 1 P a g e | 49


(E)-Dihydro-5-methyl-3-((thiophen-2-yl) methylene) furan-2(3H)-one (34Aj):

1

O

S

O

HB HX

HA

HM

1'2

4

3 6

5

7

8

Mol. Formula: C10H10O2S, Mol. Wt.: 194.25, Yellowish Crystalline solid,


IR (KBr, cm-1

) :1741.


1.49 d (J= 6.2 Hz) 3H (-CH3)



4.79 sext 1H (HX)

7.15-7.76 m 4H (HM and 3ArH)

MS (m/z) :194.95 (M)+.

13

C-NMR (CDCl3, 75 MHz) 0-150 δppm : 139.1-C1, C1’, 132.2-C2,130.0-

C3, 129.1-C4, 128.1-C5, 74.0-C6, 29.6-C7, 22.5-C8.

1.7 Bioassay

1.7.1 In-Vitro anti-cancer activity

All the synthesized α-benzylidene-γ-methyl-γ-butyrolactones 34A (a-j)

were tested for their in-vitro anti-cancer potential against human myeloid leukemia

cell K562 using Sulforhodamine B assay (SRB) [67, 68]

.

In the present protocol cells lines were grown in RPMI 1640 medium

containing 10% fetal bovine serum and 2mM L-glutamine. For present screening

experiment, cells were inoculated in to 96 well microtiter plates in 100μL at plating

densities. After cell inoculation, the microtiter plates were incubated at 370C, 5%

CO2, 95% air and 100% relative humidity for 24 hrs prior to addition of experimental

drugs. After 24 hrs, one 96 well plate containing 5 x 103 cells/well was fixed in-situ

with TCA, to represent a measurement of the cell population at the time of drug

addition (Tz). Experimental drugs were initially solubilized in dimethyl sulfoxide at

C H A P T E R 1 P a g e | 50


100mg/ml and diluted to 1mg/ml using water and stored frozen prior to use. At the

time of drug addition, an aliquot of frozen concentrate (1mg/ml) was thawed and

diluted to 100 μg/ml, 200 μg/ml, 400 μg/ml, 800 μg/ml with complete medium

containing test article. Aliquots of 10 μL of these different drug dilutions were added

to the appropriate microtiter wells already containing 90 μL of medium, resulting in

the required final drug concentrations i.e. 10 μg/ ml, 20 μg/ml, 40 μg/ml, 80 μg/ml.

After compound addition, plates were incubated at standard conditions for 48 hrs and

assay was terminated by the addition of cold TCA. Cells were fixed in-situ by the

gentle addition of 50 μL of cold 30% (w/v) TCA (final concentration, 10% TCA) and

incubated for 60 minutes at 40C. The supernant was discarded; the plates were washed

five times with tap water and air dried. Sulforhodamine B (SRB) solution (50 μL) at

0.4 % (w/v) in 1% acetic acid was added to each of the wells, and plates were

incubated for 20 min. at room temperature. After staining, unbound dye was

recovered and the residual dye was removed by washing five times with 1% acetic

acid. The plates were air dried. Bound stain was subsequently eluted with 10mM

trizma base, and the absorbance was read on a plate reader at a wavelength of 540 nm

with 690 nm reference wavelength. Percent growth was calculated on a plate by plate

basis for test wells relative to control wells. Percent growth was expressed as the ratio

of average absorbance of the test well to the average absorbance of the control wells

X 100. Using the six absorbance measurements [time zero (Tz), control growth(C),

and test growth in the presence of drug at the four concentration levels (Ti)]; the

percent growth was calculated at each of the drug concentration levels. Percent

growth inhibition was calculated as:

[(Ti-Tz)/(C-Tz)] X 100 for concentrations for which Ti >/= Tz. (Ti-Tz) positive or

zero.

[(Ti-Tz)/Tz] X 100 for concentrations for which Ti < Tz. (Ti-Tz) negative.

The dose response parameters were calculated for each test article. Growth

inhibition of 50% (GI50) was calculated from [(Ti-Tz)/(C-Tz)] X 100 = 50, which is

drug concentration resulting in a 50% reduction in the net protein increase (as

measured by SRB staining) in control cells during the drug incubation. The drug

concentration resulting in total growth inhibition (TGI) was calculated from Ti = Tz.

C H A P T E R 1 P a g e | 51


The LC50 (concentration of drug resulting in a 50% reduction in the measured protein

at the end of the drug treatment as compared to that at the beginning) indicating a net

loss of cells following treatment is calculated from [(Ti-Tz)/Tz] X 100 = -50.

The viability of cells was determined for the tested compounds at four

different concentrations 10- 4

, 10-5

, 10-6

and 10-7

moles. The in-vitro anti cancer

activity was expressed as GI50 [μm], the concentration of the compound resulting in a

50% reduction in the net protein increase. Adriamycin (Doxorubicin) was used as a

positive control drug. The results of the screening are summarized in Table 1 and the

growth curve showing activity of tested α-benzylidene-γ-methyl-γ-butyrolactones

34A (a-j) against K562 cell line as compared with the standard Adriamycin is shown

in Figure 1.22.

Table 1 In-vitro cytotoxic activity of the synthesized α-benzylidene-γ-methyl-γ-

butyrolactones 34A (a-j) against K562cell line.

34A

Values as μmoles

LC50

TGIb

GI50c

a >10 >100 36.3

b >10 >100 27.2

c >10 >100 22.9

d >10 84.9 <0.1*

e >10 97.3 28.0

f >10 78.0 14.0

g >10 93.5 <0.1*

h >10 92.1 28.4

i >10 >100 42.6

j >10 58.6 0.8

ADR >10 11.6 <0.1* aLC50: drug molar concentration causing 50% cell death.

bTGI: drug molar concentration resulting in total growth inhibition.

cGI50: drug molar concentration causing 50% cell growth inhibition.

*Compound with GI50 < 10 μmoles is consider to be active.

C H A P T E R 1 P a g e | 52


Figure 1.22 Growth curve showing activity of the synthesized α-benzylidene-γ-

methyl-γ-butyrolactones 34A (a-j) against K562cell line.

Fig. 1.22

From the results obtained, it was found that only three compounds 34Aa,

34Ab and 34Ae showed significant in-vitro anti-cancer activity. The compound 34ab

has methoxy group and compound 34Ae has benzyloxy group at C4 position of the

aromatic ring which showed anti-cancer activity with GI50 < 10μm which was equal

to that of the positive control drug (GI50 < 10μm). On the other hand, α-benzylidene-

γ-methyl-γ-butyrolactones (34Aa) exhibited a moderate activity (GI50 = 0.8μm) and

is less active than the reference drug. Finally compounds 34Ac, 34Ad, 34Af, 34Ag,

34Ah, 34Ai and 34Aj showed no activity.

These results shows that the compounds carrying an electron donating group

at the C4 position of the aromatic ring are more potent for the cell line K562 as

compared to the parent γ-butyrolactone.

The correlation between cytotoxicity and structures of compounds (34Aa,

34Ab and 34Ae) showed that the activity is enhanced by the presence of one electron

donating group only at C4 position of aromatic ring (34Ab and 34Ae). The presence

C H A P T E R 1 P a g e | 53


of other electron donating group at C3 position in addition to the group at C4 position

(34Ac) decreases the activity. Similarly, the activity decreases if two electron

donating groups are present at C3 and C5 position in addition to the one at C4

position (34Ad).

1.7.2 Anti-oxidant activity

Antioxidants are chemical compounds that can quench reactive radical

intermediates formed during the oxidative reactions. Food oxidation is one of the

main causes of food spoilage; especially in food items with a high lipid fraction.

Therefore antioxidants have been added to food items for food preservation.

All the α-benzylidene-γ-methyl-γ-butyrolactones 34A (a-j) were tested for

their anti-oxidant properties using DPPH assay.

The DPPH (2, 2−diphenyl-1-picrylhydrazyl) radical scavenging

activity of compounds were analyzed by using the method of Shimada [69]

with certain

modifications. In brief, a 0.8 ml of compound bearing specific concentration and 1 ml

of freshly prepared 0.2 mM DPPH (Sigma) solution in methanol were mixed together

to react for 30 min in dark. Blank samples contained methanol. The scavenged DPPH

was then monitored by measuring the decrease in optical density at 517 nm. %

Radical scavenging effect was defined as [O.D. Blank− O.D. Test / O.D. Blank] ×

100. The decrease in optical density was measured on Instrument UV-mini 1240,

Shimadzu, Japan.

Only the compound 34Ah showed the desired radical scavenging

activity up to 43.18%, 58.66% and 71.36% at 50ppm, 100ppm and 200ppm

respectively. The results are summarized in Table 2.

C H A P T E R 1 P a g e | 54


Table 2 Anti-oxidant activity of synthesized α-benzylidene-γ-methyl-γ-

butyrolactones 34A (a-j).

34A

50 ppm

100 ppm 200 ppm

OD at 517

%

OD at 517

%

OD at 517

%

a 1.301 -0.69 1.298 -0.46 1.298 -046

b 1.301 -0.69 1.301 -0.69 1.300 -0.61

c 1.311 -1.47 1.298 -0.46 1.298 -0.46

d 1.301 -0.69 1.311 -1.47 1.305 -1.00

e 1.308 -1.23 1.308 -1.23 1.308 -1.23

f 1.305 -1.00 1.308 -1.23 1.311 -1.47

g 1.301 -0.69 1.298 -0.46 1.274 1.39

h 0.734 43.18 0.534 58.66 0.370 71.36

i 1.324 -2.47 1.298 -0.46 1.295 -0.23

j 1.324 -2.47 1.321 -2.24 1.318 -2.01

DPPH

UV at 517 = 1.292 (Blank)

The % radical scavenging activity of the α-benzylidene-γ-methyl-γ-

butyrolactones 34A (a-j) is shown in Figure 1.23.

Figure 1.23 % radical scavenging activity of the compounds 34A (a-j).

Fig. 1.23

C H A P T E R 1 P a g e | 55


Experimental

General remarks

1. All melting points were recorded in open capillaries and are uncorrected.

Expressed in degree Celcius (0C).

2. All solvents and reagents were purified and dried according to the procedures

given in Perrin and Vogel’s text book of practical organic chemistry.

3. Infrared spectra were recorded using KBr pellets on Shimadzu Fourier

transform infrared spectrophotometer in the region 4000-400 cm-1

. The 1H-

NMR and 13

C-NMR spectra were recorded on Varian mercury plus 300 MHz

spectrophotometer in CDCl3 as solvent and TMS as internal standard with 1H

resonant frequency of 300 MHz and 13

C resonant frequency of 75 MHz. The

chemical shifts were measured in δppm downfield from internal TMSi at δ=0.

Abbreviations used are as s = singlet, d = doublet, brd d = broad doublet, t =

triplet, q = quartet and m = mulitiplate.

4. The mass spectra were recorded on Varian Inc. 410 prostar binary LC with

500 MS IT.

5. Column chromatography was performed on sd-Fine silica gel (60-120 and 200-

400 mesh). TLC was performed on Fluka® silica gel plates (5-17μm, F254).

The mobile phase was n-hexane and ethyl acetate and detection was made

using UV light and iodine vapors.

Exp. No. 1.1 Preparation of triphenyl-α-ethoxycarbonylmethylene phosphorane

(46)

Br

O

O 1. PPh3, dry benzene

2. aq. NaOHPh3P

COOC2H5

H

46

Exp. No.1.2 Preparation of carboethoxy-(α-allyl) methylenetriphenyl

phosphorane (47)

C H A P T E R 1 P a g e | 56


Ph3P

COOC2H5

H

Ph3P

COOC2H5

Br

CHCl3 /

2. aq. NaOH

1.

46 47

Exp. No. 1.3 Preparation of (E)-ethyl-2-benzylidene-4-pentenoate (48a)

H

O Ph3P

COOC2H5

O

O47

dry benzene / reflux

45a 48a

Exp. No. 1.4 Preparation of 2-benzylidene -4-pentenoic acid (49a)

O

O 3N KOH / C2H5OH

Stirr, r.t.

O

OH

48a 49a

Exp. No. 1.5 Preparation of (E) - α-benzylidene-γ-methyl-γ-butyrolactone (34Aa)

O

O

Con. H2SO4

Stirr, -100C-00CHB

HX

HA

HMO

OH

49a 34Aa

Exp. No. 1.6 Preparation of (E)-ethyl-2-benzylidene-4-pentenoates (48b-j)

H

OR1

R2

R3

R4

Ph3PCOOC2H5

R1

R2

R3

R4

O

O47

dry benzene / refluxR5

R5

45 (b-j) 48 (b-j)

C H A P T E R 1 P a g e | 57


Exp. No. 1.7 Preparation of 2-benzylidene -4-pentenoic acids (49b-j)

R1

R2

R3

R4

O

O

R1

R2

R3

R4

O

OH3N KOH / C2H5OH

Stirr, r.t.

R5 R5

48 (b-j) 49 (b-j)

Exp. No. 1.8 Preparation of (E) - α-benzylidene-γ-methyl-γ-butyrolactones

(34Ab-j)

R1

R2

R3

R4

O

OH

R1

R2

R3

R4

O

O

Con. H2SO4

Stirr, -100C-00CHB

HX

HA

HM

R5 R5

49 (b-j) 34A (b-j)

Exp. No. 1.1 Preparation of triphenyl-α-ethoxycarbonylmethylene phosphorane

(46)

This phosphorane was prepared from ethyl bromoacetate (4.18 gm, 25 mmol)

and triphenylphosphine (6.28 gm, 24 mmol) in dry benzene (35 ml) using reported

procedure [70]

(5.7 gm, 69 %), m.p. 125-1260C (lit. m.p.

[70] 125-127).

Exp. No.1.2 Preparation of ethyl 2-(triphenyl-λ5-phosphanylidene) pent-4-

enoate (47)

The phosphorane 47 was prepared by allylation of simple phosphorane 46 (5

gm, 14 mmol) using allyl bromide (2.06 gm, 17 mmol) in dry chloroform (25 ml) as

allylating agent. The reported procedure is used for the preparation of this modified

Wittig reagent [65]

(4.69 gm, 84 %), m.p. 1220C (lit. m. p.

[65] 122

0C).

Exp. No. 1.3 Preparation of (E)-ethyl-2-benzylidene-4-pentenoate (48a)

To a solution of benzaldehyde 45a (1.06 gm, 10 mmol) in dry benzene (25

ml), phosphorane 47 (4 gm, 10.3 mmol) was added and the reaction mixture was

refluxed for 3.5 hrs. Evaporation of the solvent gave a thick liquid, which on coloumn

C H A P T E R 1 P a g e | 58


chromatography over silica gel using n-hexane: ethyl acetate as an eluent (1:9), gave

the pentenoate 48a (1.98 gm, 90 %) as a thick yellowish liquide.

Exp. No. 1.4 Preparation of 2-benzylidene -4-pentenoic acid (49a)

To a solution of pentenoate 48a (0.216 gm, 1 mmol) in ethanol (5 ml) aq.

KOH (3N, 3 ml) was added and the reaction mixture was stirred at room temperature

for 1.5 hrs. Ethanol was removed, water (5 ml) added to it and acidified with ice cold

HCl (1:1). The solid obtained was filtered, washed with water and dried, to give 2-

benzylidene-4-pentenoic acid 49a (0.169 gm, 92%), m.p. 900C (lit.

[66] 90-91

0C).

Exp. No. 1.5 Preparation of (E) - α-benzylidene-γ-methyl-γ-butyrolactone (34Aa)

The pentenoic acid 49a (0.1 gm, 0.5 mmol) was added to well cooled con.

H2SO4 (2 ml) and the reaction mixture was stirred at -100c for 1 hr and then it was

allowed to reach up to 00c during 30 min. The reaction was poured over crushed ice

and the solid obtained was extracted with chloroform (3 X 15 ml). The combined

organic extract was washed successively with aq. NaHCO3 solution and water and

then dried over Na2SO4. The solid obtained after removal of solvent was recrystallised

from dichloromethane-hexane to furnish (E) - 3-benzylidene-γ-methyl-γ-

butyrolactone (34Aa) (0.092 gm, 92 %), m.p. 550c (lit.

[66] 58

0C).

Exp. No. 1.6 Preparation of (E)-ethyl-2-benzylidene-4-pentenoates (48b-j)

The mixture of aromatic aldehydes 45b-j (10 mmol) and phosphorane 47 (4

gm, 10.3 mmol) was dissolved in dry benzene (25 ml). The reaction mixture was

refluxed as mentioned against the individual compounds. The solvent was removed

and the residue obtained was coloumn chromatoghraphed over silica gel using n-

hexane: ethyl acetate (1:9) as an eluent to give the product pentenoates 48b-j as thick

liquid.

Pentenoates 48 Time

(hrs)

Yield

(%)

(E)-Ethyl 2-(4-methoxybenzylidene) pent-4-enoate (48b) [66]

3 92

(E)-Ethyl 2-(3, 4-dimethoxybenzylidene) pent-4-enoate (48c) [66]

3 92

(E)-Ethyl 2-(3, 4, 5-trimethoxybenzylidene) pent-4-enoate (48d) [66]

3 94

C H A P T E R 1 P a g e | 59


(E)-Ethyl 2-(4-(benzyloxy) benzylidene) pent-4-enoate (48e) [66]

3 88

(E)-Ethyl 2-(4-ethoxy-3-methoxybenzylidene) pent-4-enoate (48f) 3.5 94

(E)-Ethyl2-(4-(benzyloxy)-3-methoxybenzylidene)pent-4-enoate (48g) 3 85

(E)-Ethyl 2-(4-(dimethylamino) benzylidene) pent-4-enoate (48h) 3.5 90

(E)-Ethyl 2-(2-nitrobenzylidene) pent-4-enoate (48i) 3.5 88

(E)-Ethyl 2-((thiophen-2-yl) methylene) pent-4-enoate (48j) 3.5 92

Exp. No. 1.7 Preparation of 2-benzylidene -4-pentenoic acids (49b-j)

Aq. KOH (3N, 3 ml) was added to a solution of pentenoates (48b-j) (1mmol)

in ethanol (5 ml). The reaction mixture was stirred at room temperature as mentioned

against the individual compounds. Ethanol was removed; water (5 ml) added to it and

acidified with ice cold con. HCl (1:1). The solid obtained was filtered, washed with

water and dried, to gave pentenoic acids 49b-j as shown below,

Pentenoic acids 49 Time

(hrs)

Yield

(%)

(E)-2-(4-methoxybenzylidene) pent-4-enoic acid (49b) [66]

1 93

(E)-2-(3, 4-dimethoxybenzylidene) pent-4-enoic acid (49c) [66]

1 92

(E)-2-(3, 4, 5-trimethoxybenzylidene) pent-4-enoic acid (49d) [66]

1 90

(E)-2-(4-(benzyloxy) benzylidene) pent-4-enoic acid (49e) [66]

1.5 90

(E)-2-(4-ethoxy-3-methoxybenzylidene) pent-4-enoic acid (49f) 1.5 89

(E)-2-(4-(benzyloxy)-3-methoxybenzylidene) pent-4-enoic acid (49g) 1 88

(E)-2-(4-(dimethylamino) benzylidene) pent-4-enoic acid (49h) 1.5 90

(E)-2-(2-nitrobenzylidene) pent-4-enoic acid (49i) 1.5 92

(E)-2-((thiophen-2-yl) methylene) pent-4-enoic acid (49j) 1.5 90

Exp. No. 1.8 Preparation of (E) - α-benzylidene-γ-methyl-γ-butyrolactones

(34Ab-j)

The pentenoic acids 49b-j (0.5 mmol) were converted to the corresponding (E)

- α-benzylidene-γ-methyl-γ-butyrolactones 34A (b-j) using ice cold con. H2SO4 (2

ml) as described in Exp. No. 1.5 as shown above,

(E) - α-Benzylidene-γ-methyl-γ-butyrolactones 34A(b-j) Time Yield

C H A P T E R 1 P a g e | 60


(hrs) (%)

(E)-3-(4-methoxybenzylidene)-dihydro-5-methylfuran-2(3H)-one

(34Ab) [66]

1 92

(E)-3-(3, 4-dimethoxybenzylidene)-dihydro-5-methylfuran-2(3H)-one

(34Ac) [66]

1 92

(E)-3-(3, 4, 5-trimethoxybenzylidene)-dihydro-5-methylfuran-2(3H)-

one (34Ad) [66]

1 88

(E)-3-(4-(benzyloxy) benzylidene)-dihydro-5-methylfuran-2(3H)-one

(34Ae) [66]

1.5 90

(E)-3-(4-ethoxy-3-methoxybenzylidene)-dihydro-5-methylfuran-

2(3H)-one (34Af)

1.5 90

(E)-3-(4-(benzyloxy)-3-methoxybenzylidene)-dihydro-5-

methylfuran-2(3H)-one (34Ag)

1 95

(E)-3-(4-(dimethylamino)benzylidene)-dihydro-5-methylfuran-2(3H)-

one (34Ah)

1.5 88

(E)-3-(2-nitrobenzylidene)-dihydro-5-methylfuran-2(3H)-one (34Ai) 1.5 92

(E)-Dihydro-5-methyl-3-((thiophen-2-yl) methylene) furan-2(3H)-

one (34Aj)

1.5 92

C H A P T E R 1 P a g e | 61


References

[1] a] Rodriguez C. M., Martin V. S., Tet. Lett., 1991, 32, 2165.

b] Rodriguez C. M., Martin T., Ramirez M. A., Martin V. S., J. Org. Chem.,

1994, 59, 4461.

[2] a] Chapman H., Dictionary of Organic Compounds, New York, 1982.

b] Hansch C., Comprehensive Medicinal Chemistry; Ed; Pergamon: Oxford,

U.K., 1990.

[3] Yoshika H., Mabry T.J., Timmermann B.N., ‘Sesquiterpene Lactones’,

University of Tokyo press, Tokyo, 1973.

[4] Rao C. B. S., ‘Chemistry of Lignans’, Andhra Univ. Press, Vishakhapatnam,

India, 1978.

[5] Cavallito C. J., Haskell T. H., J. Am. Chem. Soc., 1946, 68, 2332.

[6] Marshall J. A., Cohen N., J. Org. Chem., 1964, 29, 3727.

[7] a] Kupchan S. M., Kelsey J. E., Maruyama M., Cassady J. M., Tet. Lett.,

1968, 31, 3517.

b] Kupchan S. M., Kelsey J. E., Maruyama M., Cassady J. M., Hemingway J.

C., Knox J. R., J. Org. Chem., 1969, 34, 3876.

[8] Mori K., Tetrahedron 1989, 45, 3233.

[9] Dubs P., Stussi R., Helv. Chem. Acta., 1978, 61, 990.

[10] Trost B.M., Salzmann T.N., Hiroi, J. Am. Chem. Soc., 1976, 98, 4887.

[11] Larson G. L., de Perez R. M. B., J. Org. Chem. 1985, 50, 5257.

[12] Lin T.T, Lu S.Y. Piperaceae in Flora of Taiwan, second ed. Editorial

Committee of the Flora of Taiwan, Taipei, Taiwan, vol. 2, 624.

[13] Chen Y. C., Liao C. H., Chen I. S., Phytochemistry 2007, 68, 2101.

[14] Flora of Taiwan, Epoch, Edited by Li H. L., Taiwan 1975, 1, 538

[15] Fang J. M., Liu M. Y., Cheng Y. S., Phytochemistry 1990, 29, 3048.

[16] Kataky R., Kanjilal P. B., Bordoloi M., Ind. J. Chem., 2005, 44B, 434.

[17] Bordoloi P. K., Bhuyan P. D., Boruah P., Bordoloi M., Rao P. G., Phytochem.

Lett., 2009, 2, 22.

[18] Hein S. M., Gloer J. B., Koster B., Malloch D., J. Nat. Prod., 2001, 64, 809.

[19] Davidson B. S., Ireland C. M., J. Nat. Prod., 1990, 53, 1036.

[20] Lee Y. N., Flora of Korea, Kyohak Sa, Seoul 1996, pp.161.

[21] Min B. S., Lee S.Y., Kim J. H., Kwon O. K., Park B.Y., An R. B., Lee J. K.,

C H A P T E R 1 P a g e | 62


Moon H. I., Kim T. J., Kim Y. H., Joung H., Lee H. K., J. Nat. Prod., 2003, 66,

1388.

[22] Csuk R., Barthel A., Schwarz S., Kommera H., Paschke R., Bioorg. Med.

Chem., 2010, 18, 2549.

[23] Choudhury A., Jin F., Wang D., Wang Z., Xu G., Nguyen D., Castoro J., Pierce

M. E., Confalone P. N., Tet. Lett., 2003, 44, 247.

[24] Padakanti S., Pal M., Yeleswarapu K. R., Tetrahedron 2003, 59, 7915.

[25] Chen Y. C., Liao C. H., Chen I. S., Phytochemistry 2007, 68, 2101.

[26] Bordoloi P. K., Bhuyan P. D., Boruah P., Bordoloi M., Rao P. G., Phytochem.

Lett., 2009, 2, 22.

[27] Hughes M. A., McFadden J. M., Townsend C. A., Craig A. T., Bioorg. Med.

Chem. Lett., 2005, 15, 3857.

[28] a] Rodriguez E., Towers G. H. N., Mitchell J. C., Phytochemistry 1976, 15,

1573.

b] Liono Y., Tanaka A., Yamashita K., Agric. Biol. Chem., 1972, 36, 2505.

[29] Spring O., Albert K., Gradmann W., Phytochemistry 1981, 20, 1883.

[30] Dupuis G., Nenezra C., Schlewer G., Stampf J. L., Mol. Immun., 1980, 17,

1045.

[31] Sequeira L., Hemingway R. J., Kupchan S. M., Science 1968, 161, 789.

[32] Kupchan S. M., Eakin M. A., Thomas A. M., J. Med. Chem., 1971, 14, 1147;

see also Kupchan S. M. in V. C. Runeckles: Recent Advances in

Phytochemistry Vol. 9, Plenum Press, New York 1975, Chapter 8.

[33] Kupchan S. M., Aynehchi Y., Cassady J. M., Schnoes H. K., Burlingame A. L.,

J. Org. Chem., 1969, 34, 3867.

[34] Cassady J. M., Suffness M., in Cassady J. M., Douros J. D.: Medicinal

Chemistry, Vol. 16: Anticancer Agents Based on Natural Product Models,

Academic Press, London 1980, Chapter 7.

[35] Ogura M., Cordell G. A., Farnsworth N. R., Phytochemistry 1978, 17, 957.

[36] Ding H. X., Lu W., Zhou C. X., Li H. B., Yang L. X., Zhang Q. J., Wu X. M.,

Baudoin O., Cai J. C., Gueritte F., Zhao Y., Chinese Chem. Lett., 2005, 16,

1279.

[37] Picman A. K., Balza F., Towers G. H. N., Phytochemistry 1982, 21, 1801.

[38] Rodriguez E., Towers G. H. N., Mitchell J. C., Phytochemistry 1976, 15, 1573.

C H A P T E R 1 P a g e | 63


[39] Gross D., Z. Chem., 1980, 20, 397.

[40] Rucker G., Angew. Chem., 1973, 85, 895; Angew. Chem. Int. Ed. Engl., 1973,

12, 793.

[41] a] Tanaka M., Mitsuhashi H., Wakamatsu T., Tet. Lett., 1992, 33, 4161.

b] Newman C. G., Ring M. A., O'Neal H. E., J. Am. Chem. Soc., 1978, 100,

5946.

[42] Tanaka M., Mukaiyama C., Mitsuhashi H., Wakamatsu T., Tet. Lett., 1992, 33,

4165.

[43] Tomioka K., Mizuguchi H., Koga K., Chem. Phar. Bull., 1982, 30, 4304.

[44] Tomioka K., Mizuguchi H., Koga K., Tet. Lett., 1978, 47, 4687.

[45] Larson G. L., de Perez R. M. B., J. Org. Chem., 1985, 50, 5257.

[46] Banerji J., Bose P., Chakrabarti R., Das B., Ind., J. Chem., 1993, 32B, 709.

[47] Lee E., Hur C. U., Geong Y. C., Rhee Y. H., Chang M. H., Chem. Comm.,

1991, 1314.

[48] Banerji J., Das B., Heterocycles 1985, 23, 661.

[49] Moritani Y., Ukita T., Hiramatsu H., Okamura K., Ohmizu H., Iwasaki T., J.

Chem., Soc., Per. Trans 1., 1996, 2747.

[50] Honda T., Kimura N., Sato S., Kato D., Tominaga H., J. Chem., Soc., Per.

Trans 1., 1994, 1043.

[51] Minami T., Niki I., Agawa T., J. Org. Chem., 1974, 39, 3236.

[52] Evans R. L., Stavely H. E., U. S. Patent 1966, 3,248,392, Chem. Abstr., 1966,

65, 2332.

[53] Matsuda I., Murata S., Izumi Y., Bull. Chem. Soc. Jpn., 1979, 52, 2389.

[54] Uematsu T., Matsuo N., Sanemitsu Y., Agric. Biol. Chem., 1984, 48, 2477.

[55] Ende H., Simchen G., Synthesis, 1977, 867.

[56] Datta A., Ila H., Junjappa H., Tetrahedron 1987, 43, 5367.

[57] Singh G., Bhattacharjee S. S., Ila H., Junjappa H., Synthesis 1982, 693.

[58] Matsui S., Bull. Chem. Soc. Jpn., 1987, 60, 1853.

[59] Tamaru Y., Hojo M., Yoshida Z., J. Org. Chem., 1991, 56, 1099.

[60] Honda, T., Kimura N., Sato S., Kato D., Tominaga H., J. Chem. Soc. Perkin

Trans-1., 1994, 1043.

[61] Bellina F., Carpita A., Santis M. D., Rossi R., Tetrahedron 1994, 50, 12029.

[62] a] Roshi R., Carpita A., Cossi P., Tetrahedron 1992, 48, 8801.

C H A P T E R 1 P a g e | 64


b] Roshi R., Carpita A., Bellina F., Cossi P., J. Organomet. Chem., 1993, 451,

33.

[63] Ballini R., Marcantoni E., Perella S., J. Org. Chem.,1999, 64, 2954.

[64] Amonkar C. P., Tilve S. G., Parameswaran P. S., Synthesis 2005, 14, 2341.x

[65] Mali R. S., Tilve S. G., Yeola S. N., Manekar A. R., Heterocycles 1987, 26,

121.

[66] Mali R.S., Babu K. N., Helv. Chim. Acta 2002, 85, 3525.

[67] Vichai V., Kirtikara K., Nat. Protocols 2006, 1, 1112.

[68] Skehn P., Storeng R., Scudiero D., Monks A., McMohan J., Vistica D.,

Jonathan T. W., Bokesch H., Kenney S., Boyd M. R., J. Natl. Cancer Inst.,

1990, 82, 1107.

[69] Shimada K., Fujikawa K., Yahara K., Nakamura T., J. Agric. Food. Chem.,

1992, 40, 945.

[70] Kuchar M., Kakac B., Nemecek O., Kraus E., Holubeck J., Coll. Czech. Chem.

Comm., 1973, 38, 447.

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